Since I did not get any response or opinions on the above post I e-mailed Kohler and have posted their reply (received in less than 24 hours) to the same questions.

THEIR REPLY:

Thank you for contacting the Kohler Company regarding technical information.

The filters are interchangeable. The difference between the two is the length and the available filter capacity mainly dictated by available filter space.

The first five hour "break-in" oil change is no longer required with today's new OHV engines. The 5 hour oil change was originally requested by almost all engine manufactures of years back when the engines were built with the "L-Head" design. You can change oil after a 5 hour run time, but it is no longer required.

Using synthetic oil in your engine does offer a few benefits. The oil viscosity is not affected by the heat the engine produces, and will retain the consistency longer. It also has better lubrication quality and will hold up longer than standard oils. There are only two concerns with the use of synthetic oils. Number one, make sure you have at least fifty hours of running time on the engine so the piston rings can break-in properly. If rings are not allowed to break-in properly you will have a noisy engine which will have a tendency to smoke and use oil. The other is to make sure you follow the same oil change intervals as when you use the standard oils. Also make sure you use 10W30 oil.

With regards to your question on fuels, Kohler recommends fuel with a rating of 87 octane or higher as well. Premium fuel is not really recommended nor is it required.